80% Rape Cases Lack DNA?

Nadir: Our friend Calvin on Sunday interjected the ludicrous claim that "80% of all rape cases procede without DNA evidence". As I tried to explain, that statistic doesn't apply to cases in which a "rape kit" is performed within hours of the alleged attack. Instead, that statistic -- to the extent that it's accurate -- applies to all rape cases filed in modern times, including the original case that this accuser tried to file ten years ago, wherein she claimed that three men had gang raped her three years previously. Obviously that case, had it proceded, would not have been untracked by lack of DNA evidence. But if three men beat and raped my mom an hour ago, what chance do you think that a microbiological rape test would fail to uncover evidence of human DNA, latex, or latex lubricant? Remember, the DA was so convinced that the testing would recover such that he essentially guaranteed it in his warrent to the judge. Did he really think there was only a 20% chance of recovering inculpatory evidence?